Automatic switch for use in telephone or like systems



June 16, 1942. G "T, BAKER 2,286,328

AUTOMATIC SWITCH FOR USE IN TELEPHONE OR LIKE SYSTEMS Filed May 11, 1959 2 Sheeis-Sfieet 1 1 29.1- 11111 -111n ab INVENTOR GEORGE THOMAS BAKER ATTORNEY June 16, 1942. G. T. BAKER 2,286,328

AUTOMATIC SWITCH FOR USE IN TELEPHONE OR LIKE SYSTEMS Filed May 11, 1939 2 Sheets-Sheet 2 INVENTOR GEORGE THOMAS BAKER ATTORNEY Patented June 16, 1942 I UNITED STATES PATENT OFFICE AUTOMATIC SWITCH FOR USE IN TELE- PHONE OR LIKE SYSTEMS ware Application May 11, 1939, Serial No. 273,034 In Great Britain May 13, 1938 19 Claims.

The present invention relates to automatic switches for use in telephone or like systems and is more particularly applicable to arrangements of the non-numerical type suitable for connecting a calling subscribers line with a first numerical switch. In the construction of automatic switches as hitherto employed in telephone systems it has been an almost universal principle that only one connection at a time can be extended over any one switch. This simplifies the mechanical and electrical arrangements but involves the provision of a considerable number of switches in an exchange of large size and consequently a large amount of bank multipling. An attempt has been made to reduce the costly bank multipling with its millions of soldered connections by the use of bare wire multiples but only with partial success. The chief object of the present invention is to reduce the number of switches by employing a construction such that a plurality of connections may be extended simultaneously over a single switch bank; this not only reduces the amount of bank multipling required but also serves an appreciable amount of space so that site and building costs can be reduced.

According to one feature of the invention in an automatic switch .a plurality of independently movable contact-making devices are each adapted to establish connection between any particular set of contacts and one of a plurality of outgoing or incoming lines common to all the sets of contacts.

According to another feature of the invention in an automatic switch a plurality of contactmaking devices adapted to engage with the same set of contacts are provided with common driving means arranged to operate the various contact-making devices independently.

A further feature of the invention is that in an automatic switch a contact-making device after being positioned to complete a connection is dissociated from its driving means and remains in association with the same set of contacts until it is required for completing another connection.

Still another feature of the invention is that in an automatic switch a plurality of contact making devices are provided and an idle device is preselected before the switch is taken into use to extend a further connection, the preselected device alone being positioned to effect the setting up of the connection.

According to another feature of the invention in an automatic switch a plurality of independently movable contact-making devices are pro- F! vided, the same driving means serving to preselect a device and to position it for extending a connection.

According to a further feature of the invention in an automatic switch a plurality of independently movable contact-making devices are each adapted to be advanced opposite a set of contacts corresponding to a marked line and subsequently to be moved to make connection therewith, the movement in each case being performed by driving means common to all the contactmaking devices.

The invention will be better understood from the following description of one method of carrying it into effect which should be taken in conjunction with the accompanying drawings comprising Figs. 1-5.

Fig. 1 is a schematic showing of the switch bank and its wipers,

Fig. 2 is a schematic showing of the switch mechanism,

Fig. 3 illustrates the wipers more in detail, and

Figs. 4 and 5 show two different constructions of the switch mechanism.

Referring first to Fig. 1, this shows the schematic layout of the switch and may be considered as a side elevation. The switch is preferably provided with a semi-circular bank of contacts forming six rows or levels. lihe upper row or level of contacts represents individual subscribers lines and the lower five rows or levels represent trunk lines, each connecting to a first selector. It will be noted that each of the lower five rows is in the form of a segment or plate extending over the whole are of the switch bank. To connect different subscribers lines to the different trunk lines, five wiper sets a, b, c, d and e are provided, one for each trunk line as shown schematically to the right f Fig. 1. As will be explained presently, each of these Wiper sets may be moved independently of the others and positicncd opposite the contacts of any subscribers line to form a bridging connection between that line and one of said contact segments. Accordingly, by using all of the wiper sets, bridging connections may exist to any five subscribers lines at the same time and each subscriber's line will be connected to a different trunk line.

It will be appreciated that while Fig. 1 indicates but a single contact for each subscribers line on the bank of the switch, this is intended to represent all of the contacts associated with that line. Ordinarily instead of a single contact or line there will be four, one each for the negative and positive conductors, one for the test conductor, one for the metering conductors. Accordingly, each of the trunk line segments will have a corresponding four conductors and each of the wiper sets will have four bridging paths in order to provide the proper connection between a subscribers line and a trunk line. One of these wiper sets is shown more in detail in Fig. 3. It will be seen that wiper set H has four wipers near the top to engage with the upper level of the contacts in the bank (1. e., subscribers lines) and somewhat below these wipers four corresponding wipers for connecting with one of the trunk line segments. These wipers are fixed in any desired manner to the common wiper carriage which may conveniently be a bar of magnetic material. The other wiper sets are similar to the one shown in Fig. 3, except that the four lower wipers are at different distances below the four upper wipers in each case, as illustrated schematically by a, b, c, d and e in Fig. 1. Each wiper set is normally inserted in the bank so as to connect a subscribers line with a corresponding set of contact segments. The circuit arrangements are such however that if the line is not in use it is not busied and no connection is extended over the wiper set in question to a first selector. The common operating mechanism diagrammatically indicated by in Fig. 2 normally stands opposite a preselected idle wiper set such as If and when a line calls, this wiper set is withdrawn from the bank in a manner to be described in detail and is rotated in search of the calling line. When the calling line is found, the wiper set is inserted so as to connect up the line to a first selector connected to the corresponding set of contact segments. The operating mechanism then advances further so as to position itself opposite the next idle set of wipers in readiness for the succeeding call. Preferably the common operating mechanism will always rotate in the same direction and when carrying a wiper set will be retracted so that the wiper set carried will clear other sets inserted in the bank, thereby to prevent fouling.

It will be understood that in order that the calling line may be identified, a wiper carried on the common mechanism must engage a suitable bank of contacts and also that a further contact bank is necessary to control the preselection of an idle set of wipers. This is indicated in Fig. 3 by the wiper designated T.

As an alternative to the method of working suggested, it could be arranged that when no movement was taking place the preselected set of wipers was withdrawn from the bank and remained associated with the operating mechanism so that the mechanism could immediately commence its hunting motion. Thus during the periods when the mechanism was at rest there would always be a set of wipers associated therewith except when all the various sets of wipers were actually in use.

It might happen if the switch were being used as a subscribers finder switch as suggested above, that a calling line already would have a set of wipers associated with it which was not the preselected set. In this case it would be necessary to prevent any damage to the switch by the mechanism attempting to plunge this latter set of wipers and the connection would be transferred to the set already in position. Preferably this transfer would be effected without any movement of the operating mechanism at all, the preselected set of wipers remaining available for the succeeding call.

Though there are certain advantages in providing only one set of wipers for each common line it might be found desirable in certain cases to make use of two or more, for instance to obtain more rapid operation. If the switch were performing the functions suggested above, only one of these sets would be effective at a time but the switch could also be arranged for connecting with both the calling and the called subscriber by the use of two sets of wipers asso- One possible method for withdrawing the: wipers and reinserting them into the bank is illustrated diagrammatically in Figs. 2 and 3.-

When a call is initiated, assuming that the driving mechanism is already positioned opposite an idle set of wipers, magnet I4 is energised to cause magnet I2 to engage the wiper set and then mag-- net I2 is energised and withdraws the wiper set in question from the-bank on the de-energisation of magnet l4. Magnet [3 is then operated to cause the whole mechanism I0 to be stepped until the wiper set is opposite the calling line and when this is reached magnet I4 is energised momentarily to cause the wipers to be plunged into the bank and magnet I2 is then ole-energised. When magnet I4 is released shortly thereafter the mechanism is restored to a position in which it does not foul any of the wipers and further operation of the magnet 13 takes place to effect preselection of the next idle wiper set.

Considering now the actual construction illustrated in Fig. 4 in plan, this incorporates the general principles indicated in Fig. 2 and it is assumed that the switch is generally similar to the well-known rotary switches of the electromagnetically-operated pawl and ratchet type as commonly used. in telephone systems. These switches are generally arranged on the reverse drive principle, that is to say, the energisation of the driving magnet results only in the driving pawl slipping over one tooth of the ratchet wheel, while when the magnet is tie-energised the armature restoring spring advances the ratchet wheel and associated wipers one step.

In Fig. 4 the actual driving magnet is not shown but the pawl is represented by and it will be understood that when the magnet is energised, this pawl is moved to the left while when the magnet is de-energised it again moves to the right and rotates the ratchet wheel 2| one step. Mounted on the same spindle as the ratchet wheel 2| are the scissor arms 22 and 23, which, as shown, are symmetrical about the axis of rotation and carry at their opposite ends the magnets 24 and 25 which are used for the purpose of withdrawing wiper sets. A magnet 26 is secured to the scissor arm 23 by the strap 21 and this magnet co-operates with the soft iron bar 28 which is secured to the scissor arm 22 by the strap 29. The scissor arms are normally held in the position shown by the springs 30 and 3 l, the limiting position being determined by the strips 32 and 33.

Considering now the operations which take place when a call is initiated, it will be assumed that the mechanism is already standing opposite a preselected set of wipers 34 (corresponding to the wiper set I l of Figs. 2 and 3) and that the call is on a line other than that which the said wipers are engaging. Magnet 26 is first operated and this causes magnets 24 and 25 to be moved radially outward to engage the soft iron framework of the wiper set 34. Magnets 24 and 25 are also energised at this time so that when magnet 26 is de-energised, which now takes place, the wiper set 34 is withdrawn from the bank due to the action of the restoring springs 30 and 3|. The main driving magnet is now energised and operates by self-interruption to rotate the mechanism until the wiper set 34 is opposite the calling line. Thereupon the mechanism comes to rest and magnet 26 is energised to cause the wipers to be inserted into the bank. Thereafter magnets 24 and 26 are de-energised so that the wiper set 34 is left in the bank and the magnet 24 is withdrawn so that it will not foul any of the wiper sets during the subsequent rotary operation. The main driving magnet is then again energised to cause the mechanism to step itself opposite the next available idle wiper set.

It will be appreciated that with the doubleended arrangement shown which has certain advantages on the ground of symmetry it would preferably be arranged that whichever of the magnets 24 and 25 was away from the bank had a wiper set permanently associated with it so as to enable the operation to be properly continued when the end of the mechanism which has been adjacent the contacts moves past the end of the bank. Alternatively, if the slight extra hunting time were not considered objectionable, the mechanism could be made single-ended only, in which case arrangements would of course be made to balance the magnet 24 and also the magnet 26. It will be understood, of course, that connections to magnets 24, 25 and 26 are made by suitable slip rings.

Fig. shows a further constructional arrangement in which, however, the wiper set to be moved is not picked up by magnetic attraction but by a direct gripping action. This permits the operating magnet to be located in any convenient, position and though in the arrangement shown neither the magnet 24 nor the magnet 26 is shown actually on the axis of rotation to avoid complicating the drawings, this location could be adopted without difficulty and would result in a reduction in the moment of inertia of the rotating system. In 'Fig. 5 the same references are employed as in Fig. 4 to indicate corresponding parts.

It will be seen that the arrangement in this case is single-ended and that the scissor arms 22 and 23 instead of being pivoted about the axis of rotation are pivoted at 40 on aplate 4| secured to the ratchet wheel 2! by the screws 42 and 43. The magnet 26 is again secured to the scissor arm 23 by the strap 21 and the co-operating soft iron bar 28 is secured to the scissor arm 22 by the strap 29. In this case the scissor arms are adapted to effect radial movement of a plate 44 which carries magnet 24 and also the members 45 and 46 of a tongs arrangement. seen that when magnet 24 is energised at a time when magnet 26 is also energised, the members t5 and 46 will grip the wiper set 34 and can thus be used for withdrawing it and carrying it to a different position. The tongs members '45 and 46 are restored to normal by the springs 41 and 4.8 and the limits of their movement are set-by the slotted link 49. Preferably there will be a pin or V-shaped connection between the end of the tongs and the framework of the wiper set so as to ensure that it is properly positioned in front of any set of contacts and has no tendency to become detached during the rotary movement.

It will be understood that though the switch has been shown with five wiper sets, the actual number provided is dependent on various considerations. Conveniently the number of wiper sets would be sufficient to deal with all the traflic from the group of subscribers represented by the full capacity of the switch which might be 50 or It Will be points. In this case each subscribers line would appear only once and no multipling would be involved unless it were thought desirable to provide a reserve switch to prevent the whole group being put out of action by a defect in the mechanism.

It will be appreciated also that although the invention has been described in connection with a non-numerical switch for associating a calling line with a first numerical switch for which purpose it offers special advantages, certain of the principles involved are also applicable to numerical switches though with suitable modifications to meet the somewhat different conditions.

I claim:

1. In a unitary switch structure, a contact bank in which terminate lines of two different classes, each of the lines of one class appearing but once in said bank, a plurality of circuit clos-- ers corresponding respectively to the lines of the other class, and a mechanism common to said circuit closers for operating any one thereof to cause that circuit closer to complete a circuit via said contact bank between the line of said other class to which that circuit closer corresponds and any line of said one class.

2. In a unitary switch structure, a plurality of primary lines each terminating but once in the switch, a plurality of secondary lines each having an individual contact making device, and a mechanism common to said devices for operating any of said devices to cause that device to complete a circuit between its associated secondary line and any desired primary line.

3. In a unitary switch structure, a plurality of primary lines each terminating but once in the switch, a plurality of secondary lines each having an individual contact making device, and a mechanism common to said devices for operating any one of said devices to cause said one device to complete a circuit between its associated secondary line and any one of said primary lines and then operating any other of said devices to cause said other device to complete a circuit be tween its associated secondary line and another of said primary lines before said first circuit is broken.

4. An electrical switch including a bank of con tacts, a plurality of devices each adapted to mechanically engage any of said contacts to com-- pl'ete an electrical circuit over that contact, and an electrically controlled mechanism common to said devices and also common to said contacts for operating any of said devices independently of the other devices to engage a desired one of said contacts.

5. An electrical switch including a bank of contacts, a plurality of devices each adapted to mechanically engage any of said contacts to complete an electrical circuit over that contact, and an electrically controlled mechanism common to said devices and also common to said contacts for operating any one of said devices to engage one of said contacts and then operating any other of said devices to engage another of said con .tacts while said first device remains engaged with said one contact.

6. In an automatic switch, a plurality of stationary circuit terminals, a plurality of independently movable circuit terminals, and a remotely controlled electromechanical mechanism common to said movable terminals for engaging any one thereof with any one of said stationary terminals.

'7. In an automatic switch, a plurality of stationary circuit terminals, a plurality of independently movable circuit terminals, and a remotely controlled electro-mechanical mechanism common to said movable terminals for engaging any one thereof with any one of said stationary terminals, each stationary terminal being en" gaged at the same point at different times by the different ones of said movable terminals.

8. In a switch, a plurality of primary line terminals and a plurality of secondary line terhas been selected to cause the circuit closer associated with the selecting mechanism at that time to complete a circuit from the selected primary line terminal to one of said secondary line terminals.

9. In a switch, a plurality of primary line terminals and a plurality of secondary line terminals, a plurality of circuit closers each common to all of said primary line terminals, a selecting mechanism, means for operating said mechan'mm at difierent times to select different individual ones of said primary line terminals, different ones of said circuit closers temporarily associated with the selecting mechanism during the different ones of said selecting operations, and means common to all of said circuit closers operated when one of said primarly line terminals has been selected to cause the circuit closer associated with the selecting mechanism at that time to complete a circuit from the selected pri mary line terminal to one of said secondary line terminals.

10. In a switch for closing an electric circuit over any contact of a plurality appearing in the contact bank of said switch, a selector mechanism, means for moving said mechanism to select any individual one of the contacts, a member carried and supported exclusively by said mechanism during the selection of an individual contact, means operated to transfer said member from said mechanism to the contact bank when an individual contact has been selected, said member being thereafter supported on said bank independently of said mechanism and effective to close a circuit over the selected contact.

11. A mechanical switching arrangement for r use in telephone or like systems, including a plurality of jacks, a plurality of plugs, a mechanism common to said plugs and jacks, and electrically controlled means for operating said mechanism to insert any plug in any jack to complete an electrical connection therebetween.

12. A mechanical switching arrangement for use in telephone or like systems, including a plurality of jacks, a plurality of plugs each adapted to be inserted in any of said jacks to complete an electrical connection thereover, a mechanism common to said plugs and jacks, and electrically controlled means for operating said mechanism to remove any plug from any jack.

13. An automatic switch for selectively controlling any of a plurality of circuits terminating in said switch, including a normally retracted lazy-tongs mechanism, means operated to move the lazy-tongs mechanism in retracted condition to select any individual one of said circuits. and

means then operated to extend the lazy-tongs mechanism to control the selected circuit.

14. In an automatic switch, a plurality of contacts of one class, a plurality of contacts of another class, a laterally and endwise movable plunger common to all contacts of both classes, and means for operating said plunger at times to make connection between any contact of one class and any contact of another class and at other times to break connection between any contact of one class and any contact of another class.

15. In combination, a plurality of lines, a plurality of switches each adapted to close a connection to any of said lines, a step-by-step device common to said switches for controlling the selective operations of same, and means on said common device for mechanically operating the switches to close connections to selected lines.

16. In an automatic switch, a plurality of contacts of one class, a plurality of contacts of'another class, a unitary selecting member common to all of the contacts of both classes, and means operated to impart to said member two separate and distinct movements in succession, thereby to close a circuit between any contact of said one class and any contact of said other class.

17 In an automatic switch, a plurality of contacts of one class, a plurality of contacts of another class, a circuit closed between any contact of one class and any contact of the other class, a unitary member common to all of the contacts of both classes, and means operated to impart to said unitary member two separate and distinct movements in succession thereby to interrupt said circuit.

18. In an automatic switch, a plurality of stationary contacts, another stationary contact common to said first contacts, a movable contact also common to said first contacts and normally disconnected from all of said stationary contacts, means for moving said last contact to a position opposite any desired one of said first contacts, and means for then moving said last contact to engage said one contact and said other stationary contact, thereby to form a bridging connection between said one and said other contact.

19. In an automatic switch, two groups of stationary contacts, one of said groups comprising a larger number of contacts than the other, a movable contact for each stationary contact in the smaller one of said groups, each of said movable contacts normally engaging its corresponding stationary contact in the smaller group and also engaging some one of the stationary contacts in the larger group, thereby to complete an electrical circuit over itself from its corresponding stationary contact in the smaller group to the Stationary contact in the larger group, and a mechanism common to said movable contacts for disengaging any of said movable contacts from the stationary contacts with which it is engaged, for moving said movable contact while thus disengaged, for then re-engaging it with its corresponding stationary contact in the smaller group and for engaging it also with a stationary contact of the larger group other than the contact of that group with which it was previously engaged, whereby each of said movable contacts can complete a circuit over itself from its corresponding stationary contact in the smaller group to any stationary contact in the larger group.

GEORGE THOMAS BAKER. 

